What type of antenna is typically found on modern aircraft and is characterized by its flat oval or teardrop shape?

The type of antenna commonly found on modern aircraft that is characterized by its flat oval or teardrop shape is typically recognized as a directional antenna. Directional antennas are designed to focus energy in a specific direction, effectively increasing the range and quality of communication or radar signals. This shape, often seen in advanced avionics, helps optimize the signal for specific frequencies while minimizing interference from other sources.

The distinctive flat oval or teardrop design allows for effective aerodynamic integration into the aircraft's structure, reducing drag while maintaining performance. Such antennas can be used for various purposes, including communication, navigation, and surveillance systems, which are critical for the safe operation of modern aircraft.

In contrast, omnidirectional antennas radiate signals in all directions equally, dipole antennas usually have a more traditional elongated shape, and parabolic antennas focus signals in a specific direction but typically have a dish shape. Therefore, the characteristics of a directional antenna align perfectly with the description provided in the question.